[CentOS] Is ext4 safe for a production server?

> If they do what you want without making you wait, why even consider changing the 
> filesystem that has been working for years on these machines?
>   

Adding new, bigger disks and new filesystems? Wanting these to be the 
fastest that is reasonably possible?
As for the system that arose the question (again) for me, I've decided 
to make it ext3, wait for a while as ext4 matures, and convert it later.
This interesting possibility made me decide for ext3 (again).